Comparison of in situ and ex situ reduced graphene oxide reinforced electroless nickel phosphorus nanocomposite coating

Electroless nickel-phosphorus (EN)-reduced graphene oxide (rGO) composite coating was carried out to compare the ex situ route of reinforcement of reduced GO in EN coating (EN-rGO) and in situ route of reinforced of rGO in EN coating (EN-GO). The coatings were characterized using X-ray diffraction (XRD) and attenuated total reflectance infrared spectroscopy (ATR-IR) for phase determination and to show the presence of reinforcement of rGO in the coatings respectively. ATR-IR spectra indicated that GO was chemically reduced in situ while deposition of EN-GO composite and thermal reduction during its heat treatment. XRD pattern of heat treated EN-GO coating show the change in preferred orientation of nickel deposit. Upon heat treatment, the hardness of EN and EN-GO and EN-rGO deposits increased while the corrosion resistance decreased except for EN-GO coating. The hardness of EN-rGO and EN-GO coating is approximately half the value of EN deposit. The electrochemical polarization studies indicated that EN-GO deposit was corrosive resistant than EN-rGO and EN deposit.